The present invention is directed to conditioning shampoo formulations prepared from specific cationic polymers, anionic surfactants and optional nonionic surfactants. The resultant shampoo formulations are economical to prepare, exhibit improved lathering and possess commercially acceptable conditioning properties.
The need for a shampoo formulation which conditions (i.e. renders the hair more manageable) as it cleans has long been recognized in the art. Thus, while conditioning agents for application to already shampooed hair have long been known, it has only been within recent years that conditioning shampoos have become available. A number of these shampoos are specially formulated for mildness and hence, low detergency, so as to leave a portion of the hair's natural oils behind. Consequently the hair soon looks and feels greasy and dirty. Other formulations contain certain oily components, such as polyglycols, fatty acid esters of glycols, natural or synthetic waxes or lanolin derivatives, which components are deposited on the hair during shampooing. The oily nature of such components, however, inhibits lathering of the shampoo and also contributes to the feeling of greasy, dirty hair soon after shampooing.
A third type of conditioning shampoo contains a cationic polymer which can deposit on the hair during shampooing to impart the desired degree of manageability while overcoming the previously described problem of greasiness development. The primary difficulty encountered in preparing such shampoo conditioners has been that of achieving a stable system without destroying the delicate balance of conditioning and other functional properties. Previous attempts to provide solubility of the conditioning polymer while achieving suitable cleaning and lathering as well as deposition of the polymer on the hair have resulted in the finding that specific polymers when incorporated with amphoteric surfactants (detergents), optionally in the presence of nonionic or ionic surfactants, will result in shampoo formulations which condition as they clean. Such findings are due to the superior compatibility of the amphoterics with the commonly used cationic polymers thereby allowing maximum deposition of the polymer onto the hair during shampooing.
Thus, U.S. Pat. No. 4,009,256 issued Feb. 22, 1977 and assigned to the assignee herein, discloses a conditioning shampoo comprising an aqueous solution of (1) a cationic polymer which is a water-soluble acid salt of an aminoalkyl ester of a carboxylic acid polymer, (2) an amphoteric detergent, and (3) optionally, at least one nonionic surfactant or at least one ionic surfactant or a combination thereof, wherein any plurality of ionic surfactants utilized consists of those of the same ionogenic class. The necessity for employing the amphoteric detergent in such formulations is supported and reinforced by substantially all the patents directed to conditioning shampoos. Thus, U.S. Pat. Nos. 3,313,734; 3,962,418; 2,999,069; 3,055,836; 3,996,146 and 3,400,198, among others, require the presence of an amphoteric or polar non-ionic component in order that the conditioning polymer be compatible with the remaining ingredients in the shampoo formulation. Of all the pertinent art known to applicants, only U.S. Pat. No. 3,816,616 discloses a conditioning shampoo which does not require the presence of a compatibilizing agent and such teaching is directed only to the use of one very specific cationic polymer--a quaternized modified cellulosic polymer.
The primary disadvantages to the requirement for an amphoteric detergent or surfactant to be present in conditioning shampoo formulations are related to their high cost and weak foaming ability relative to the anionic surfactants available. Thus the use of amphoteric surfactants substantially increases the cost of producing conditioning shampoos, thereby limiting the consumer market to which the products may be directed.
It is therefore an object of the present invention to provide a conditioning shampoo which can be prepared in the absence of an amphoteric component.
It is a further object to prepare an economical, effective conditioning shampoo.
These and other objects will be apparent from the description which follows.